DESCRIPTION My long term goal is to elucidate the molecular mechanisms of recognition and activation of chemokine receptors, a subfamily of G protein-coupled receptors, which plays a key role in inflammation, angiogenesis, tumorogenesis and as co-receptors for the entry of HIV-1. The aim of this project is to produce well ordered 3-D crystals of a G protein-coupled receptor in collaboration with Dr. Landau at the Biocenter in the University of Basel. We plan to crystallize and solve the structure of cephalopod rhodopsin, a prototype (3 protein-coupled receptor. This receptor is highly expressed in photoreceptor membranes, is stable in detergents and upon reconstitution into lipid vesicles assembles into two-dimensional crystals. For the formation of three- dimensional crystals we will employ the novel procedure developed by Dr. Landau, which involves insertion of the protein into a continuous three- dimensional bilayer matrix afforded by lipid cubic phases. Using this approach Dr. Landau crystallized bacteriorhodopsin, a-light-driven proton pump, and solved the structure of this protein at a resolution of 2.5 angstroms (Science 277, 1676-1680, 1997). Elucidation of the structure of a o protein-coupled receptor will be essential to interpret the many genetic and biophysical studies on these proteins in molecular terms. I am planning three visits, each of four months. Crystallization and X-ray experiments are new areas of research for the applicant, therefore the first term most likely will involve learning crystallization of proteins and some X-ray analysis. The second and third terms will involve crystallization trials with rhodopsins from different cephalopod rhodopsins, and some preliminary X-ray experiments.